In some instances after a well has been drilled to its total depth, it is decided for various reasons to produce from a formation much shallower than the depth drilled, requiring the circulation of cement to plug the open hole below the formation to be produced. In some cases, a good cement job is not attained, allowing dangerous and expensive communication of fluid past the cement plug to thereby risk loss of the well, loss of life and environmental pollution.
The use of an inflatable packer as taught by U.S. Pat. No. 3,918,522 improves the seal between the zones by squeezing mud from between the borehole and the resilient sleeve to effect an immediate seal which is both faster and of greater integrity than a conventional cement seal which cannot squeeze out the mud. After the producing formation has been penetrated, hydrocarbons under pressure are subject to flowing up the well bore to the surface, making every hour of rig time more dangerous thereafter. Since the inflatable packer seals immediately on inflation and since check valves maintain the sealing pressure as the cement hardens and after, a permanent seal and a faster and safer method of completions now becomes possible. The usual rig time delay caused while a conventional cement plug hardens is no longer necessary, and the next operation can proceed sooner and in greater safety than heretofore.